A cost-effective Co3O4@WO3 hetero-structure derived from WO3@Co-CoPBA for oxygen evolution reaction

The oxygen evolution reaction (OER) is hindered by the sluggish kinetics, high costs, and poor stability of noble metal catalysts (e.g., RuO2), as well as low atomic utilization and limited accessibility of active sites in transition metal oxide catalysts. To address these challenges, this study develops a core-shell structured WO3@Co-CoPBA heterostructure as an efficient OER electrocatalyst. Co-CoPBA nanocubes are hydrothermally synthesized and then loaded with WO3 nanorods, followed by gradient annealing under N2 atmosphere (optimized at 500 °C) to form a Co3O4@WO3 heterojunction. Characterization and electrochemical evaluations reveal that annealing at 500 °C induces topological reconstruction of Co-CoPBA into porous Co3O4 and graphene cores, Co sites in Co3O4 serve as the catalytic active centers, forming a strong electronic coupling interface with the WO3 shell. This architecture significantly enhances the density of active sites (electrochemically active surface area of 3.8 cm2) and charge transfer efficiency (Tafel slope of 55.12 mV dec-1). The catalyst delivers an overpotential of 315 mV at 100 mA cm-2 in 1 M KOH, outperforming commercial benchmark catalyst RuO2 (372 mV). It exhibits exceptional stability with almost no performance decay after 100 h. Density functional theory (DFT) calculations demonstrate that interfacial electronic restructuring modulates the d-band center, optimizing the adsorption Gibbs free energy of OOH* intermediates and thereby improving intrinsic catalytic activity. This work provides an effective interface engineering strategy for designing high-performance, low-cost transition metal-based electrocatalysts.